Former Manchester United striker Wayne Rooney believes the club are still missing two quality players to compete with top teams. He said that besides Benjamin Sesko, Manchester United need another reliable goalscorer and also need to invest in the full-back position.
The No. 9 role and full-back positions are two gaps

Rooney believes that if Manchester United want to compete for major trophies, they need a consistent finisher in the squad. Sesko is still young and adapting to English football, and he needs time to develop into a prolific attacking option for Manchester United. Adding another striker this summer would have been an ideal move, but United focused much of their effort on strengthening the midfield.
The full-back position was also mentioned by Rooney. Luke Shaw is unlikely to play every match, and the team could have used another option to share the workload. Manchester United were linked with Newcastle United's Lewis Hall, but ultimately did not complete the necessary addition.
Rooney's original comments on the podcast
On the “Stick to United” podcast, Rooney said: “I just feel that the Everton game confirmed my feeling. Manchester United were the better side, they had strong control of the match, but they lacked a No. 9. Whatever the reason, Sesko was not fully recovered and he missed pre-season.”
It remains unknown whether the issue can be addressed in January
Whether Manchester United can solve this problem in January remains to be seen. Rooney acknowledged that Shaw is a quality player, but given his injury history, the team cannot expect him to play every match and also need squad rotation.
Based on Rooney's assessment, Manchester United's summer transfer strategy left two clear gaps: a lack of a second scoring option in attack and insufficient rotation depth on the left side of defence. Without strengthening these areas, the margin for error will become smaller during a congested schedule and high-level matches.